46 A MANUAL OF MOSSES 



Order II. ANDRBABALBS. 



Small, monoicous (or dioicous), dark brown to almost 

 black, when dry very brittle, mostly cespitose on granite or 

 slate rocks : stems slender, radiculose below, dichotomous, with 

 - fascicled branchlets, no central strand ; leaves small, crowded, 

 erect-spreading to often falcate-secund, uni-stratose to partly 

 bi-stratose, thickish, often more or less papillose, costate to 

 ecostate, very opaque ; cells small, incrassate : seta none, but 

 represented by a pseudopodium from the gametophore ; capsule 

 oval, opening by 4 (-8) vertical slits, the valves remaining 

 united both above and below ; spores and columella derived 

 from the endothecium ; no air-cavity between the spore-sac and 

 the capsule-wall ; calyptra torn at the base, delicate ; spores 

 large, about .034 mm. in diameter, chlorophyllose. 



This peculiar order is represented by but one family, the 

 Andreaeaceae, which consists of only one genus, Andreae [Ehr- 

 hart] Hedwig. There are about 90 species, alpine or sub-alpine 

 and widely distributed; 13 species occur in North America, only 

 3 of which, however, are to be expected in our range. 



I. ANDRBABA [Ehrhart] Hedwig. 



a. Leaves ecostate. i. A. rupestris. 



a. Leaves costate. b. 



b. Leaf elongate-lanceolate ; costa filling only about the middle one- 

 third of the leaf-apex. 2. A. rothii Weber and 



Mohr. 

 {A. rupestris Roth), 

 b. Leaf lanceolate-subulate ; costa practically filling the whole apex 

 of the leaf. 3. A. crassinervia Bruch. 



1. Andreaea rupestris Hedwig. 



(A. petrophila Ehrhart). 



Densely cespitose, dark brown to blackish : stems slender, 

 about 1.5-2.5 cm. high, usually branching, more or less erect; 

 leaves when dry very brittle, crowded, small, ovate to lance- 

 ovate, imbricated, often falcate-secund from an erect base, 

 usually obtuse, entire, margin incurved ; no costa ; (the leaves 

 are so dense that they usually require bleaching in a solution of 

 caustic potash before the leaf-cells can be made out under the 

 microscope) ; basal leaf-cells narrow-rectangular, very incras- 

 sate, sinuose, above becoming shorter, the median and upper 

 cells rounded and angular-oblong, longitudinally seriate, 

 dorsally strongly papillose: fruit similar to that of Sphagnum 

 in being enclosed in the perichaetium until mature, when it is 

 quickly exserted on an outgrowth from the tip of the leafy 

 shoot similar in appearance to a short seta and termed the 

 pseudopodium ; calyptra very thin and irregularly torn at base ; 



